The present invention concerns an improved hinge for a seat, in particular for an automobile vehicle, and a seat provided with said hinge.
One prior art hinge for a seat, in particular for an automobile vehicle, is of the type comprising:
two connecting flanges, one of which is fixed and is adapted to be fixed to a seat cushion and the other which is mobile and is adapted to be fixed to a seat squab or backrest, said flanges being adapted to turn relative to each other about a hinge axis that is substantially perpendicular to them, PA1 a hinge control member mounted to rotate about the hinge axis at least one way from a rest position, and PA1 means for spring loading the control member into its rest position including means for approximate positioning of said control member. PA1 the control member has a generally cylindrical shape and is carried by at least one bearing in the fixed flange and the accurate positioning means comprise at least one thrust spring bearing radially between the fixed flange and a flat for positioning the control member so as to spring load the flat into a position coinciding with the accurate rest position of the control member; PA1 the thrust spring is a generally U shape leaf spring having two plane branches in radial bearing engagement, a fixed branch against an edge of a recess in the contour of the bearing and a mobile branch against the positioning flat, the thrust spring spring loading the flat into a position substantially parallel to that of its branches; PA1 the flat is delimited by a substantially concave surface so as to limit contact of the mobile branch with the flat substantially to two generatrices of the control member; PA1 the free end of the mobile branch has two attachment lugs disposed between one face of the fixed flange and a shoulder on the control member, the attachment lugs extending transversely to the control member, on respective opposite sides of said member; PA1 the attachment lugs are housed in a recess on the face of the fixed flange compensating the thickness of the lugs; PA1 the hinge further includes means for coupling the flanges together actuated by two rotary rings centred substantially on the hinge axis, each comprising a lug on their inside contour, the control member being provided with a cam disposed between the two lugs, adapted to cooperate selectively with said two lugs by rotating in opposite directions, the approximate positioning means for the control member including a circumferentially acting spring hooked onto the lugs, so as to spring load the rings in opposite directions tending to place the control member in its rest position by cooperation of the two lugs with the cam of the control member; PA1 the spring is a split ring the axial edges of which are hooked into the lugs; PA1 the rings can be moved in two opposite directions respectively to adjust the inclination of the squab and to fold it forwards, between a first position of attaching at least one coupling member respectively to the first and second flanges and a second position releasing said member; PA1 the coupling member is a lever which can turn about a bearing point which, when said lever is attached to a flange, is fixed relative to that flange.
FR-A-2 739 812 (FR-95 12 159), corresponding to U.S. Pat. No. 5,857,746 describes a hinge of this type including means for coupling the flanges together actuated by two rotary rings each having a lug on its inside contour. The control member has a cam between the two lugs. The spring loading means urge the control member towards its approximate rest position by virtue of cooperation of the two lugs and the cam on the control member. This approximate position is acceptable in that there is an angular clearance between the lugs and the cam on the control member on each side of the cam.
However, in some cases this angular clearance can give rise to unwanted vibration of the control member and imprecise positioning of the manoeuvring handle usually attached to the control member.